Flue gases produced by combustion of fossil fuels and various other industrial operations in utility and industrial plants often contain sulfur dioxide (SO2) that coverts to sulfuric acid and other acidic gases. Such gases are known to be hazardous to the environment and their emission into the atmosphere is closely regulated. These acidic gases can be removed from the flue gases through a wet flue gas desulfurization (FGD) process in a gas-liquid contactor, i.e., a flue gas scrubbing apparatus, in which the flue gas is contacted with a slurry fluid that can absorb the SO2 and SO3. One type of gas-liquid contactor utilizes a spray tower (hereinafter a “tower”) in which flue gases are flowed upwardly through a descending shower of the slurry fluid. This slurry fluid typically comprises limestone (CaCO3) or other materials. The calcium-based slurry reacts with SO2, SO3 to create calcium sulfite (CaSO3) and calcium sulfate (CaSO4). Calcium sulfate is used in various building materials. Calcium sulfite is a waste material. By injecting air in sufficient quantities, the calcium sulfite reacts with the oxygen in the air to form usable calcium sulfate.
Air and oxygen are usually added in a pool of slurry material at the base of the tower. The released air/oxygen cause the slurry fluid to foam and expand into a flue duct inlet into the tower causing complications.
To prevent this, the portion of the tower holding the slurry fluid is built larger to accommodate the expanded slurry material causing them to become more expensive.
Currently there is a need for an efficient low-cost tower design.